You post something that you would say "That's what she said" after. Then again, and again, you get the idea.

EXAMPLE:

Poster 1: This is so big!

Poster 2: That's what she said! That's a long ride!

and repeat the process.

I'll start:

That was a fun ride!

"They'll hunt me; They'll condemn me; Set the dogs on me; Because that's what needs to happen. Because sometimes, the truth isn't good enough. Sometimes, people deserve more. Sometimes, people deserve to have their faith rewarded. Not because they want to, not because of chance, but because they deserve to."